1. Field of the Invention
The present invention generally relates to the danger proximity warning field and, in particular, to a wireless danger proximity warning system and method.
2. Description of Related Art
When it comes to public safety and personal safety, it is always desirable to improve upon the way people are warned about potentially dangerous situations. For example, traditional railroad collision avoidance systems are inadequate. Presently, there are approximately 259,000 railroad crossings in the United States of which approximately 22% are active railroad crossings which means that they are protected by some sort of railroad collision avoidance system. The conventional railroad collision avoidance system uses warning lights and retractable gates to alert a motorist that there is an oncoming locomotive. This means that over 200,000 railroad crossings are passive railroad crossings, which are particularly dangerous since they have no warning lights or retractable gates to warn a motorist that a locomotive is approaching the railroad crossing. Even with the use of conventional railroad collision avoidance systems at the active railroad crossings and the lack of collision avoidance systems at passive railroad crossings there is still an unacceptable number of train-vehicle accidents. For instance, in 1999, there were 399 deaths and 1360 people seriously injured in train-vehicle accidents in the United States.
In past years, several railroad collision avoidance systems have been patented in an attempt to reduce the number of train-vehicle accidents. One such system was described in U.S. Pat. No. 4,942,395 which appears to disclose a wireless railroad grade crossing motorist warning system that warns motorists traveling within a given proximity of a railroad crossing that there is an oncoming train. The wireless railroad grade crossing motorist warning system uses a three-transceiver system, wherein the oncoming train has a mounted transceiver that communicates a warning radio signal to a transceiver located at a railroad grade crossing which, in turn, emits a coded radio signal to a transceiver unit located within a motor vehicle. Unfortunately, the wireless railroad grade crossing motorist warning system uses conventional radio communication technology and as such suffers from the traditional problems associated with that technology including, for example, interference from other radios, high power consumption and multipath interference.
Another system was described in U.S. Pat. No. 5,864,304 which appears to disclose a railroad-crossing warning system for protecting pedestrians and motorists from an oncoming train. In one embodiment, the railroad-crossing warning system has six magnetic probes that cover a 40×40 foot area in the railroad crossing that detects the presence of a stalled vehicle. If there is a stalled vehicle, the railroad-crossing warning system communicates information about the stalled vehicle to the oncoming train. In addition, the railroad-crossing warning has a series of wireless trackside devices that are equally spaced along the length of the railroad track for detecting the presence of the oncoming train at a specified location and time and for determining vital warning information about the oncoming train. The train warning information is transmitted to a two-sided light emitting (LED) display located at the railroad crossing. While this system is an improvement over many others it is still subject to interference from other transmitters and must operate within an assigned frequency that can be adversely affected by different types of interference commonly associated with traditional communication technology. Accordingly, there has been a need for a railroad collision avoidance system and method that can effectively warn a person when there is a locomotive in their vicinity. There is also a need for other types of danger proximity warning systems that can be used to warn people about a wide variety of dangerous situations like the presence of a dangerous vehicle or a person under house arrest that has left their home. These needs as well are satisified by the danger proximity warning system and method of the present invention.